[jongio]

What & why

Adds a composable suite of GitHub Copilot CLI statusline extensions (pr-statusline, issue-statusline, and subagent-statusline), cross-platform interactive setup scripts (install-statusline.ps1, install-statusline.sh, and scripts/setup-statusline.mjs), and an annotated visual guide on the showcase website (site/src/pages/index.astro and site/public/pr-statusline-doc.html):

• extensions/pr-statusline: Tracks pull requests worked on in the active session across repositories and worktrees, rendering color-coded pills (Green, Amber, Red, Purple) with clickable OSC 8 links (owner/repo#number), CI check counts, merge conflict alerts, review approvals, and review thread progress.
• extensions/issue-statusline: Renders a separate clickable pill per tracked GitHub issue with priority or bug labels, linked open PR indicator, assignee handle, comment count, and purple closed-completed auto-dismissal.
• extensions/subagent-statusline: Aggregates background subagents spawned by the session into live phase counters (starting, in PR, merged, and failed) with purple all-merged auto-dismissal.
• Shared compositor & interactive setup (compose.mjs, scripts/setup-statusline.mjs, install-statusline.ps1, install-statusline.sh): Prompts for which statuslines to enable (Pull Requests, GitHub Issues, and/or Subagents) and configures ~/.copilot/statusline-compose.mjs and ~/.copilot/settings.json.
• Website showcase (site/src/pages/index.astro, site/public/pr-statusline-doc.html): Places Copilot CLI Statuslines first on the homepage with the Pull Requests | Issues | Subagents overview diagram, per-statusline annotated infographics, 18 up-close 2x-zoomed token crop screenshots, inline copy buttons, and a full-size click-to-zoom image viewer.

Validation

• node scripts/lint.mjs: Passed (112 .mjs syntax-checked, 19 .json parsed)
• node scripts/validate-extensions.mjs: Passed (9 extension(s) valid)
• node scripts/run-tests.mjs: Passed (9 test file(s) passed)
• npm test (in site/, running astro build && node test/smoke.test.mjs): Passed (9 checks passed)

Type

• New extension
• Fix / improvement to an existing extension
• Tooling / CI / docs

Checklist

• node scripts/lint.mjs passes
• node scripts/validate-extensions.mjs passes
• node scripts/run-tests.mjs passes
• New/changed extension has a smoke test under extensions/<name>/test/
• README extensions table updated (when adding or removing an extension)